Ancient Australian Rocks Show Water Reached Deep Mantle Billions of Years Ago

Analysis of rocks from Western Australia indicates that water was transported into Earth's deep interior more than three billion years ago, before modern plate tectonics fully developed. The researchers propose that water-rich crustal fragments periodically sank into the planet, fueling volcanic activity.

The discovery pushes back the timeline for when water first began cycling through Earth's deep interior, suggesting this process was active during the planet's earliest geological era. These ancient rocks, preserved in Western Australia, serve as chemical time capsules that record conditions from a period when the planet's surface and interior behaved very differently than they do today.

This finding challenges previous assumptions that deep water transport required fully developed plate tectonics. Instead, the research points to a more episodic process, where water-rich crustal fragments periodically descended into the mantle. That sinking material would have released water and other volatiles, potentially driving early volcanic activity and shaping the young planet's atmospheric and surface evolution in ways scientists are only beginning to understand.